What is characteristic of a cardiac shunt?

A cardiac shunt is characterized by the abnormal flow of blood within the heart or great vessels, deviating from the normal circulatory pathway. This flow typically occurs from an area of higher pressure to an area of lower pressure, which is a fundamental principle in hemodynamics.

When a shunt occurs, arterial blood – which is rich in oxygen – can flow into venous areas, leading to mixing of oxygen-rich blood with oxygen-poor blood. This mixing can happen due to conditions such as atrial septal defects or ventricular septal defects, where there are openings in the septum separating the chambers of the heart.

Therefore, the complete picture of a cardiac shunt includes all the listed characteristics: blood flowing from high pressure to low pressure, the unusual pathway allowing arterial blood to flow into the venous system, and the resultant mixing of oxygenated and deoxygenated blood. Each of these attributes specifically defines the nature of a shunt and highlights the dysfunction it creates within the normal circulatory system.